Rotary pump or compressor



July is, 1944. j

ROTARY vPUMP OR COMPRESSOR Filed June 18, 1941 4 Sheets-Sheet 1 G. R. MEAQDOR I 2,353,965 v July 18, 1944.

G. R. MEADOR 2,353,965 I ROTARY PUM? OR COMPRESSOR Filed June 18, 1941 ,4 Sheets-Sheet 2 July 18, 1944. G. R. VMEADOR V v 2,353,965.

ROTARY PUMP OR COMPRESSOR Filed June 18, 1941 4 Sheets-Sheet 5 July 18, 1944. G, R, M ADOR 2,353,965

ROTARY PUMP OR COMPRESSOR Filed June 18, 1941 4 Sheets-Sheet 4 IIIIIIII;%

v Patented July 18,

I OFFICE ROTARY PUMP R COMPRESSOR Gordon R. Meador, Fresno, Calif., assignor to Meador-Calender Corporation, Fresno, Calif., a corporation of California Application June 18, 1941, Serial No. 398,585

6 Claims.

This invention relates to rotary compressors, pumps, and the like, of the type employing slidable vanes.

The object of the invention is to provide 8. r0- tary compressor or pump having a higher efliciency. More particularly, the object of the invention is to provide a rotary pump or compressor which will deliver a greater volume of fluid under a higher pressure with less power, while at the same time providing an apparatus having a longer useful life. A further part of the major object of the present invention is to provide a totary pump or compressor which will give a higher volumetric efllciency.

The rotary pump or compressor of the present invention is provided with rigid vanes intended to slide diametrically in operation throughthe rotor and present its opposite ends for contact with the wall of the chamber within which the rotor is operating. As heretofore constructed, rotary pumps or compressors of such type have rapidly worn the contact edges of the vanes, resuiting in considerable slippage of fluid by the vanes, so that such rotary compressors have had the disadvantage of possessing a low efliciency and a relatively short useful life.

I'have discovered that these disadvantages can be eliminated and a rotary pump or compressor provided which is capable of operation for long periods of time without appreciable wear of the vanes and without loss of efilciencythrough slippage of the fluid being pumped by the vanes.

These improvements are attained in accordance with the present invention by certain changes in the shape of the contact surface of the vanes and changes in the contour of the'bore of the compressor with which the opposite ends of such vanes are made to contact.- These changes are essentially cooperating changes and consist flrst-oi the provision of a vane for operation within the bore of the pump or compressor, which vane has contact faces at'its ends, each so formed as to contact the bore of the pumping chamber at substantially the leading edge of the vane during the compression portion of the cycle of operation, and so formed as to (in com: bination with the contour of the bore) transfer its point of contact with the bore rearwardiy of the leading edge of the vane during other portions of the cycle of operation of the vane. The explanation for the high'efllciency oi. the rotary pump or compressor of the present invention is thought to reside in the fact that where the point of contact of the vane with the bore of the'rotor during the compression portion cycle oioperation is made to occur at substantially the leading edge of the vane, there is little or no opportunity for the pressure of the fluid being pumped or compressed to work under the vane and between its contact face and the bore of the compression chamber. Accordingly, the vane is not wedged by the compression of the fluid being pumped away from the wall of the bore and slippage of fluid by the vane is thereby avoided. In this respect, it is believed that the comparative inefliciency of the more usual type of vane compressors is due to the fact that the vanes employed therein are originally so designed, or in operation wear to a condition, so that their contact with thebore of the compression chamber takes place at substantially the center of the vane, and accordingly the fluid being pumped can exert its pressure towards forcing the vane from tight contact with the bore 01' the compression chamber,

A further characteristic of the rotary compressor or pump of the present invention is that-due to the contact of the vane with its leading edge against the bore of the compression chamber during the compression cycle it appears that satisfactory operation is secured even though the vane may have worn to a point somewhat small-' er than the width of the bore to be spanned by the vane, any slippage of fluid by the vane thus taking place on the suction rather than the compression side of the vane. Another characteristic of the rotary compressor or pump of the present invention is such wear as may take place upon the contact face of the .vane (which is extraordinarily small) operates to properly shape the contact face of the vane. so as to insure and hold its point of contact with the bore of the compressor during the compression portion of the cycle at substantially the-leading edge of the vane. I

The foregoing properties and modes of action of the vanes in the rotary pump or compressor of the present invention are dependent not only upon a vane having a proper contact face, but upon the employment in the rotary pump or compressor of a bore inthe compression chamber against which the vanes are to contact, which bore has a selected curvature especially designed to permit the aforesaid manner of cooperation between the contact face of -the vane and the walls of the bore. "The speciflc nature of the selected curvature of the bore of the pumping chamber of thepresent invention is diflicult to describe in words and will be most fully understood from the hereinafter contained description of the manner of forming or cutting such a bor in the pumping chamber of the rotary comcharge portion of the pump chamber being larger than the uction portion.

The present invention also includes means designed for improving the volumetric efllciency of the pump or compressor. Rotating compressors or pumps of the vane type operate at relatively high speeds. Thus, the peripheral speed of the vanes may be in the neighborhood of 3,000 feet per minute and in excess of the speed at which air or other fluid may be passed through the in- 1 take of the compressor or pump. As the vanes pass the end of the suction chamber, a vacuum may be formed behind the vanes, and the volumetric eiliciency of the compressor pump is re-.

duced. I have found that the volumetric emciency of such a rotary pump or compressor may be materially increased by the provision or a suitable pocket in the wall of the pumping chamber, which pocket is located close to the end of the suction chamber of the pump or compressor. This pocket I consider to be acting as an ejection chamber. The fluid handled by the pump or compressor is pressed outward by centrifugal force as the vane approaches the pocket, and elected from said pocket immediately back of the vane as it passes the pocket, thereby breaking vacuum otherwise there existing, with the result that the volumetric efllciency of the pump or compressor is very materially increased.

The rotary compressor or pump of the present invention also includes certain sealing members associated with the vane of the compressor designed to improve the efllciency of the pump or compressor by forming an improved seal with the side walls of the pumping chamber. I

Various further objects and advantages of the present invention will be apparent from a description of a preferred form or example of a rotary pump or compressor embo y ng the present invention. For .that purpose, I have hereafter, in connection with the accompanying drawings, described one preierred form of the rotary compressor embodying the present invention.

In the drawings:

tion, of the cutting end of the cutter shown in Fi e 7.

Referring to the drawings, the pump or compressor comprises a ring-shaped center casing member 2 and two end casing members 3 and 4. The center casing member 2 and the end casing members 3 and 4 are suitably secured together, as by bolts 5, and are provided with passages to form a continuous water jacket. The end casing member 3 is indicated as provided with a water inlet 8 leading to water passages, such as l, in the ring-shaped casing member 2, from which return bends, such as 8, in the end casing memher and similar water passages carry the water until the water is finally discharged from the water outlet 9 leading from the end casing memher 3.

The water thus enters the jacket at the hottest part of the compressor and flows thence to the outlet in such a manner that the heat is taken from the hottest part by the incoming water and carried over the cooler part of the compressor adjacent the intake, whereby the compressor is maintained at arelatively even temperature.

The ring-shaped casing member 2 has a bore 9, the specific shape of which is of particular importance to the invention and will be further described later. Mounted in the bore 9 is 8. cylindrical rotor ill of a length substantially equal to the length of the bore. This rotor l0 practically contacts the bore 9 along a theoretical axially extending line at one point 1!, preferably at 90 from the bottom of the bore. The rotor i0 is indicated as having certain openings II for the purpose of reducing its weight,

and another threaded opening I3 for securing suitable end heads i4 and lB-to the rotor ID. The end heads are provided with reduced por- .tions I8 and "engaged by antifriction bearings l8 and I! in the end casing members 3 and 4. A drive shaft 20 extends from the end head l5. .Suitable sealing rings 2! and 22 are supported by the end-casing members 3 and 4 for making -sealing contact with the end heads i 4 and II.

The articular form of-machine illustrated is intended to operate as an air compressor and is indicated as having its rotor ill made up of four segments spaced apart to provide diametricallyv intersecting slots 23, -in', which are mounted Figure 1 is an elevation mainly in vertical section.

Figure 2 is a section on the line 2-2 of Figure 1.

Figure 3 is a sectional elevation of the rotor.

Figure 4 is an enlarged diagrammatic view of the curved pumping chamber walls and with the rotor and its vanes therein for the purpose of showing a specific curvature of said bore and its relationshipto the rotor and vanes.

Figure 5 is a perspective of one of the vanes.

Figure 6 is a fragmentary section on the line 8-6 of Figure 5.

Figure 'l is a diagrammatic view illustrative of the initial steps employed in forming the curv bore of the pumping chamber. v

Figure 8 is a similar diagrammatic view indicathe final steps in cutting or forming the desired curvature of the pumping chamber.

Figure 9 is a fragmentary view. partially in secimpeller vanes 24 0f a length suitable to main-" tain their opposite edges in contact with the bore 8 of the ring-shaped casing member 2. While in the particular pump or compressor shown two of such impeller vanes 24 are indicated, one only may be employed, and only a single vane should be employed if the apparatus is to be employed as a liquid pump.

Where two ofv such vanes are employed, each is provided with an opening 28 leading from one side to the center, as shown in Figure 5, of a suitable width to allow the two crossing vanes to move radially of the rotor relative to each other for the amount necessary. Sealing or compression members 28 for engagement with the flat walls 21 o! the end casing members 3 and 4 are inserted in recesses in the sides and ends of the vanes 24 at their leading edges. the sealing members 28 having an enlarged locking head 28 operating to prevent the sealing members from being moved radially outward by centrifugal action. The sealing members 28 are also provided with concave rearward faces 28 at their rear edges to facilitate entrance oi. compressed air back of the sealing members 28, whereby to force the sealing members laterally outward into assaoes proper sealing contact with the straight walls 21 of the end casing members 2 and 4.

In order to lubricate vanes 24 in a simple and effective manner, the end head i4 is provided with a lubricant feed tube 3| and oil passages 22 in said head to radiate andcommunicate with the adjacent end of. longitudinal oil passages 22 formed in the rotor II on opposite sides of and adjacent the slots 22. Outlets 24 from the passages 22 at intervals lead to the walls of the slots.

A umping chamber is formed, the outer wall of which is formed by the specially shaped bore 9 of the ring-shaped casing member 2 and the straight side walls 21 of the end casing members 3 and 4. The inner wall of the pumping chamber is formed by the cylindrical surface of the rotor Ill. The pumping chamber may be considered as divided into two portions-a suction portion and a compression portion; the suction portion lying above the diametric plane passing through the axis of the rotor and the elemom; i l of the rotor most nearly approaching the bore 9, whereas the compression portion of the chamber lies below such diametric plane. The casing member 2 is indicated as provided with an outlet 35 leading from the compression'p'ortion passing out substantially tangential to the bore 9. The casing member 2 is also indicated as provided with a relatively large inlet 24 leading to as a part of the complete compressor. The rotor 4|.has a diametrical slot carrying a cutter 42 of a length substantially equalto the diameter of the cylindrical bore 28 now existing in the casing member 2. Originally, the axis ofthe rotor is made to coincide with the axis of the cylindrical bore 38. The cutter employed is provided with a cutting point 42 located at its leading edge, the cutter being intended to be rotated in theprocess by the rotor 4| in the same direction as the intmded direction of rotation of the vanes of the pump, which direction is clockwise, as viewed in either Figures 1 or 7. The cutter 42 is provided with a contact point 44 on its end opposite from itacutting point, and this contact point is located at the center of the, cutter. The cutter is also indicated as preferably provided at its cutting the inlet portion of the'pumping chamber. .The

outlet passage connects with only a relatively shortarc of the discharge portion of the pumping chamber, whereas the inlet passage 2! er:- tends over a considerably greater. arc than the suction portion of the umping chamber. The inlet passage 38 'is terminated at a point just preceding the point where in the design of the compressor the centrifugal pressure imparted to the air would otherwise tend to force the air to kick backward into the intake passages Close to the termination of the intake passage, there is provided a curved transverse pocket 21, which pocket faces towards the direction of movement of fluid in the pumping chamber and is so designed as to catch air thrown outward by thefast-moving vanes 24 as the vanes pass the said pocket and re-direct such air back into the pumping chamber immediately back of the vane as the vane passes the pocket 21, thereby acting as a sort of injection pocket to break the vacuumv description will be given of the method of forming or cutting the desired bore in the casing member 2. For this purpose, reference is, therefore, made first to Figure 7 of the drawings. In forming the desired bore 8 of the casing member 2, the casing member 2 is originally provided with a cylindrical bore, represented by the circle 38, in Figure 7, which circle 38 has a center 32 and a diameter 40. The first step in shaping the cylindrical bore to the desired curvature 2 is accomplished by. placing within the casing memher 2 a rotor 4|, which rotor may be of substantially the same size as the rotor II to be included edge with spring-pressed contacts 43a for the purpose of bearing against .the bore adjacent the cutting point for holding the cutter against its contact point 44, so that the cutting point will be held away from cutting contact with the bore except where the width of the bore is less than the span of the cutter. Accordingly, the cutter 42, as it is placed within the bore 22. originally contacts the bore at its cutting point 42 and contact point 44, which it will be observed are 'on a line which does not pass through the center of the rotor. In consequence of this, the subsequent cutting operations will efi'ect an asymmetrical removal of material from the cylindrical bore 28.

To initiate the cutting operations. the axis 45,

of the cutter is shifted from the axis of the cylindrical bore 38 along a diameter of the bore 38 leading to the point or line at which it is desired to have the rotor most nearly contact finished bore 9 of the casing member. The displacement, indicated in Figure 7, l is clearly exaggerated. The movement of the center 4' of the rotor from thecenter I! of the cylindrical bore 48 is only sufiicient to permit a proper depth cut to be made by the cutter 42. A cut is then made in the bore 38 by the cutter 42 by rotating the cutter 42, the cutter 42 being given suitable axial motion so as to cut or completely ream the bore 30. During this cutting or reaming operation, the

cutter 42' is diametrically shifted through the rotor 4| in accordance withthe guiding of the cutter 42 by the contact of its guide point 44 with f the original cylindrical surface 38, the guide point 44 being of a suflicient width to be guided by the original surface 28 rather than the new I cut surface of the bore.

During such initial cutting operation, the original cylindrical bore 34 will be modified in the manner indicated by the dotted line 44. As indicated by the dotted line 48, as the cutting point 42 leaves the horizontal position towards the bottom of the bore, as viewed in Figure 7, it proceeds to remove material from the bore "to an increasing depth until it arrives at a vertical position with its cutting point at the bottom-of the bore, as viewed in Figure 7. whereafter the depth of the cut will decrease until the cutter is again in substantially the horizontal position. As the cutting point travels upwardly from the horizontal position, it again cuts to an increasing depth until it arrives at substantially a vertical position, after which the depth of the out again decreases while the cutting point is returning to the horizontal position. The depth at which the cutter cuts while passing downwardly from the horizontal position is considerably more than the depth of the cut made as the cutting point'passes upwardly from the horizontal. The removal of the material takes place mostly at the lower half of the bore, which lower half is to form the compression portion of the pumping chamber.

At two points in the rotation of the cutter, the cutter removes substantially no material from the original bore 38. One of such points is the point where it is desired. to have the rotor substantially contact the bore 9 of the casing in the finished pump. The other point, marked 46a, is in advance of the diametric plane through said first point and the axis of the rotor. Thus, the portion of the cylindrical bore 38 that is operated upon by the cutter during its rotation through the upper portion of its cycle is more than 180, while the portion of the bore operated upon by vious cutting operations, and accordingly there results a bore 9 of the shape indicated in Figure 4, in which the lower portion of the bore the cutter during the lower part of its movement,

as viewed in Figure 7, is less than 180.

After the completion of the initial cut, the axis 45 of the rotor 4! is again shifted from the original axis 39 of the original cylindrical bore 38 a suitable distance to allow for taking a further cut, and the cuttin operation proceeds as before. continued in this manner, each time shifting the axis 45 of the rotor 4i along the diametric plane and away from theaxis 39 until the axis 45 has been shifted approximately two-thirds of the necessary distance to bring the surface of the rotor 4| in contact with the bore. During each of the subsequent cuts, the diametric shifting of the cutter through the rotor as guided by the guide point 44 of the cutter is regulated by the contact of said guide point on the previous out form of the bore. .As each subsequent cut proceeds, the cutting becomes more and more confined to the portion of the bore below the diametric plane, and particularly the lower lefthand quadrant of the bore, as viewed in Figure 7; to a somewhat lesser extent, the upper lefthand quadrant, as viewed in Figure '7, while the cutter soon begins to miss contact entirely with the bore in the upper right-hand quadrant of the bore, as viewed in Figure 7, and later the lower right-hand quadrant ofthe bore, as viewed in Figure 7.

After the cutting operation has proceeded in the manner described until the axis of the rotor H has been shifted about two-thirds of the intended distance, the remaining cutting opera-- tions are performed in the manner indicated in Figure 8. If the operations were continued in the manner described in connection with Figure 7, the final borecut in the casing member 2 would be of such a shape that no vane of fixed length could maintain itself in contact with the bore during rotation. The final cutting operations are, therefore, performed, as indicated in Figure 8, by a cutter 41. The cutter 41 is indicated as having a cutting point 4! on its leading edge. The guide point 4! of the cutter 41 is, however, shifted so as to be also substantially at the leading edge of the cutter, so that a line passing through the guide point 49 and cutting The cutting or reaming of the bore is ure 4, the point of contact between the left end below the horizontal diametric plane, including the axis of the rotor I0, is larger than the upper portion of the bore.

Thus, the original circular bore 38' (Figure 7) is enlarged by the cutting operations so that it becomes generally elliptical due to the removal of portions substantially crescent-shaped in cross section upon the opposite sides of a horizontal plane passing through the axis of the bore 38. Furthermore, the distance along a diametrical plane of the pumping chamber substantially at right angles to said horizontal plane is greater on one side of said horizontal plane than on the other, but in each instancev is greater than the radius of the bore 38. The generally crescentshaped portions removed from the bore are asymmetrical and the greatest radial dimension of the cresent-shaped portion disposed below the aforementioned horizontal plane is approxismaller crescent-shaped portion comprises asuction chamber communicating with the inlet 38 and the larger crescent-shaped portion comprises a compression chamber communicatin with the outlet 35.

In Figure 4 of the drawings, there is also diagrammatically indicated the rotor lll of the pump and the vanes 24. The vanes 24 of the pump are indicated as having their contacting ends provided with specially shaped curved contact ends 50. The impeller vanes 24 are made longest at the leading edges of the vanes and relieved slightly rearwardly from the leading edge. When the curvature of the contact ends of the vanes 24 are of the type described and such vanes are working in a bore 9 of the shape previously described, the point- 5| of contact between the vanes and bore of the casing member 2 shifts during rotation of the vanes 24. When the vanes are horizontal, as viewed'in Figof the vane and the bore takes place substantially at the leading edge of the vane. As the vane rotates through the initial portion of the point 48 will include also the axis 45 of the rotor suction chamber, thepoint of contact between the vane and bore 9 shifts rearwardlyto the center or beyond the center of the vane. Thereafter, the point of contact of the vane of the bore again shifts forwardly, as indicated in the drawings, and is throughout the compression portion of the movement of the vane close to the leading edge of the vane approaching more nearly the leading edge as it passes to the end of the compression portion of the cycle.

In consequence of the fact that the contact point between the vanes 24 and the bore 8 is at or near the leading edge of the vane throughout the compression stroke, the pressure of the fluid undergoing compression finds little opportunity for forcing the vane away from contact with the bore, and accordingly slippage of fluid by the vane during the compression portion of the cycle is substantially eliminated. It is furthermore found that wearing of the contact ends of the vanes is almost completely eliminated and that any wear which takes place is of a character such as to maintain the proper shape upon the ends of the vanes. Furthermore, it is found that where vanes are worn or initially insorted in a machine of slightly smaller size than necessary to span completely the bore 9, such vanes will maintain firm contact with the bore 9 during the compression portion of the cycle and allow slippage, if any, to take place at the suction portion of the cycle. This follows. from the fact that during the compression portion of the cycle the vane 24 shifts or slides bodily relative to the rotor l so that the leading edge of the vane moves in a direction toward said rotor, such sliding movement being resisted by slight but sumcient friction to maintain the leading edge of the vane 24 in contact with the inner curved surface of the bore 9 during said compression portion of the cycle.

For the above reasons, I have found that the rotary compressor or pump of the present invention as distinguished from those heretofore existing has an increased eiiiciency and is capable of considerably longer life.

While the particular form of rotary compressor or pump herein described is well adapted to carry out the objects of the present invention, it is to be understood that various modiflcations and changes may be made, and this invention is of the scope set forth in the appended claims.

I claim: a

1. A rotary pump or compressor comprising: a

housing having a pumping chamber of generally elliptical contour, said housing having an inlet port leading to said pumping chamber and an outlet port leading from said pumping chamber; a rotatable cylindrical rotor within said pumping chamber arranged to contact thewall of said pumping chamber at ,a predetermined point along asubstantially theoretical line extending axially of said pumping chamber, said point of theoretical line contact being disposed between said inlet and said outlet ports; at least one impeller vane carried by said cylindrical rotor and being diametrically slidable with respect to said cylindrical rotor and having ends adapted to contact with the inner wall of said pumping chamber, the dimension of said pumping chamber along a diametricai plane passing through said point of theoretical line contact and the axis of rotation of said cylindrical rotor being approximately equal to the distance between the leading edges of the opposite ends of said vane, and the distance along a diametrical plane of said pumpingchamber at'right angles to said first-mentioned plane being greater on one side of said first-mentioned plane than upon'the other, but in each instance being greater than the radius of a true circle of a diameter corresponding to that of said first dimension, whereby said pumping chamber is enlarged to a greater extent upon one side of said diametrical plane than upon the other and deviates from a true circle by asymmetrical crescent-shaped portions respectively disposed upon opposite sides of said first-mentioned diametrical plane, one of said crescentshaped portions communicating with saidinlet port and the other of said crescent-shaped portions communicating with outlet port.

2. A rotary pump or compressor as defined in claim 1, in which tbegreatest radial dimension of one of the crescent-shaped portions is ap proximately twice that of the greatest radial dimension of the other crescent-shaped portion.

3. A rotarypump or compressor as defined in claim 1, in which the greatest radial dimensionof one of said crescent-shaped portions is approximately twice that of the greatest radial dimension of the other crescent-shaped portion, and in which the smaller crescent-shaped portion comprises a suction chamber and communicates with the inlet port and in which the larger crescent-shaped portion comprises a compression chamber and communicates with the outlet port.

4. A rotary pump or compressor as defined in claim 1, in which one of the crescent-shaped portions extends through a greater are than the other crescent-shaped portion.

5. A rotary pump or compressor, comprising: a housing including a pumping chamber having a curved wall, said housing having an inlet passage and an outlet passage communicating with said pumping chamber; a cylindrical rotor in said pumping chamber; and an impeller vane carried by said rotor in contact with said curved wall, said housing having an injection pocket formed therein provided with an opening communicating with said pumping chamber, said opening being located beyond but adjacent to the innermost point of mergence of said inlet passage with said pumping chamber, said injection pocket being separated from said inlet passage by said impeller vane in one position of said impeller vane and being adapted to receive fluid forced outwardly by the movement of said impeller vane as it travels past said innermost point of mergence and starts to compress .said fluid, said injection pocket being operable to inject said fluid into said pump chamber back of said impeller vane as the trailing edge of said vane passes across the opening of said injection pocket.

6. A fluid compressor, comprising: a housing including a pumping chamber having a curved wall, said housing having an inlet passage and an outlet passage communicating with said pumping chamber; rotor means in said pumping chamberincluding an impeller portion in operating contact with said curved wall, said housing having an injection pocket formed therein provided with an opening communicating with said pumping chamber, said opening being located beyond but adjacent to the innermost point of v mergence of said inlet passage with said pumping chamber, said injection pocket being separated from said inlet passage by said impeller portion in one position of said impeller portion and being adapted to receive fluid forced outwardly by the movement of said impeller portion as it travels past said innermost point of mergence and starts to compress fluid in said pumping chamber, said injectionpocket being operable to inject said fluid into said pumping chamber back of said impeller portion as the trailing part of said impeller portion passesacross the opening of said injection pocket.

GORDON R. MEADOR. 

